GstValue

GstValue — GValue implementations specific to GStreamer

Functions

#define GST_MAKE_FOURCC()
#define GST_STR_FOURCC()
#define GST_FOURCC_ARGS()
#define GST_VALUE_HOLDS_INT_RANGE()
void gst_value_set_int_range ()
gint gst_value_get_int_range_min ()
gint gst_value_get_int_range_max ()
void gst_value_set_int_range_step ()
gint gst_value_get_int_range_step ()
#define GST_VALUE_HOLDS_BITMASK()
void gst_value_set_bitmask ()
guint64 gst_value_get_bitmask ()
#define GST_VALUE_HOLDS_INT64_RANGE()
void gst_value_set_int64_range ()
gint64 gst_value_get_int64_range_min ()
gint64 gst_value_get_int64_range_max ()
void gst_value_set_int64_range_step ()
gint64 gst_value_get_int64_range_step ()
#define GST_VALUE_HOLDS_DOUBLE_RANGE()
void gst_value_set_double_range ()
gdouble gst_value_get_double_range_min ()
gdouble gst_value_get_double_range_max ()
#define GST_VALUE_HOLDS_LIST()
#define GST_VALUE_HOLDS_ARRAY()
void gst_value_list_append_value ()
void gst_value_list_prepend_value ()
void gst_value_list_concat ()
void gst_value_list_merge ()
guint gst_value_list_get_size ()
const GValue * gst_value_list_get_value ()
#define GST_VALUE_HOLDS_FRACTION()
void gst_value_set_fraction ()
gint gst_value_get_fraction_numerator ()
gint gst_value_get_fraction_denominator ()
gboolean gst_value_fraction_multiply ()
gboolean gst_value_fraction_subtract ()
#define GST_VALUE_HOLDS_FRACTION_RANGE()
void gst_value_set_fraction_range ()
const GValue * gst_value_get_fraction_range_min ()
const GValue * gst_value_get_fraction_range_max ()
void gst_value_set_fraction_range_full ()
#define GST_VALUE_HOLDS_DATE_TIME()
#define GST_VALUE_HOLDS_CAPS()
void gst_value_set_caps ()
const GstCaps * gst_value_get_caps ()
#define GST_VALUE_HOLDS_CAPS_FEATURES()
void gst_value_set_caps_features ()
const GstCapsFeatures * gst_value_get_caps_features ()
#define GST_VALUE_HOLDS_STRUCTURE()
void gst_value_set_structure ()
const GstStructure * gst_value_get_structure ()
#define GST_VALUE_HOLDS_BUFFER()
#define gst_value_get_buffer()
#define gst_value_set_buffer()
#define gst_value_take_buffer()
#define GST_VALUE_HOLDS_SAMPLE()
#define gst_value_get_sample()
#define gst_value_set_sample()
#define gst_value_take_sample()
#define GST_VALUE_LESS_THAN
gint (*GstValueCompareFunc) ()
gchar * (*GstValueSerializeFunc) ()
gboolean (*GstValueDeserializeFunc) ()
gboolean gst_value_is_fixed ()
void gst_value_register ()
void gst_value_init_and_copy ()
gchar * gst_value_serialize ()
gboolean gst_value_deserialize ()
gint gst_value_compare ()
gboolean gst_value_can_compare ()
gboolean gst_value_union ()
gboolean gst_value_can_union ()
gboolean gst_value_subtract ()
gboolean gst_value_can_subtract ()
gboolean gst_value_intersect ()
gboolean gst_value_can_intersect ()
gboolean gst_value_is_subset ()
void gst_value_array_append_value ()
guint gst_value_array_get_size ()
const GValue * gst_value_array_get_value ()
void gst_value_array_prepend_value ()
gboolean gst_value_fixate ()

Types and Values

Object Hierarchy


Includes

#include <gst/gst.h>

Description

GValue implementations specific to GStreamer.

Note that operations on the same GValue from multiple threads may lead to undefined behaviour.

Last reviewed on 2008-03-11 (0.10.18)

Functions

GST_MAKE_FOURCC()

#define GST_MAKE_FOURCC(a,b,c,d)        ((guint32)((a)|(b)<<8|(c)<<16|(d)<<24))

Transform four characters into a guint32 fourcc value with host endianness.

1
guint32 fourcc = GST_MAKE_FOURCC ('M', 'J', 'P', 'G');

Parameters

a

the first character

 

b

the second character

 

c

the third character

 

d

the fourth character

 

GST_STR_FOURCC()

#define GST_STR_FOURCC(f)               ((guint32)(((f)[0])|((f)[1]<<8)|((f)[2]<<16)|((f)[3]<<24)))

Transform an input string into a guint32 fourcc value with host endianness. Caller is responsible for ensuring the input string consists of at least four characters.

1
guint32 fourcc = GST_STR_FOURCC ("MJPG");

Parameters

f

a string with at least four characters

 

GST_FOURCC_ARGS()

#define             GST_FOURCC_ARGS(fourcc)

Can be used together with GST_FOURCC_FORMAT to properly output a guint32 fourcc value in a printf()-style text message.

Parameters

fourcc

a guint32 fourcc value to output

 

GST_VALUE_HOLDS_INT_RANGE()

#define GST_VALUE_HOLDS_INT_RANGE(x)    (G_VALUE_HOLDS((x), gst_int_range_get_type ()))

Checks if the given GValue contains a GST_TYPE_INT_RANGE value.

Parameters

x

the GValue to check

 

gst_value_set_int_range ()

void
gst_value_set_int_range (GValue *value,
                         gint start,
                         gint end);

Sets value to the range specified by start and end .

Parameters

value

a GValue initialized to GST_TYPE_INT_RANGE

 

start

the start of the range

 

end

the end of the range

 

gst_value_get_int_range_min ()

gint
gst_value_get_int_range_min (const GValue *value);

Gets the minimum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT_RANGE

 

Returns

the minimum of the range


gst_value_get_int_range_max ()

gint
gst_value_get_int_range_max (const GValue *value);

Gets the maximum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT_RANGE

 

Returns

the maxumum of the range


gst_value_set_int_range_step ()

void
gst_value_set_int_range_step (GValue *value,
                              gint start,
                              gint end,
                              gint step);

Sets value to the range specified by start , end and step .

Parameters

value

a GValue initialized to GST_TYPE_INT_RANGE

 

start

the start of the range

 

end

the end of the range

 

step

the step of the range

 

gst_value_get_int_range_step ()

gint
gst_value_get_int_range_step (const GValue *value);

Gets the step of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT_RANGE

 

Returns

the step of the range


GST_VALUE_HOLDS_BITMASK()

#define GST_VALUE_HOLDS_BITMASK(x)      (G_VALUE_HOLDS((x), gst_bitmask_get_type ()))

Checks if the given GValue contains a GST_TYPE_BITMASK value.

Parameters

x

the GValue to check

 

gst_value_set_bitmask ()

void
gst_value_set_bitmask (GValue *value,
                       guint64 bitmask);

Sets value to the bitmask specified by bitmask .

Parameters

value

a GValue initialized to GST_TYPE_BITMASK

 

bitmask

the bitmask

 

gst_value_get_bitmask ()

guint64
gst_value_get_bitmask (const GValue *value);

Gets the bitmask specified by value .

Parameters

value

a GValue initialized to GST_TYPE_BITMASK

 

Returns

the bitmask.


GST_VALUE_HOLDS_INT64_RANGE()

#define GST_VALUE_HOLDS_INT64_RANGE(x)    (G_VALUE_HOLDS((x), gst_int64_range_get_type ()))

Checks if the given GValue contains a GST_TYPE_INT64_RANGE value.

Parameters

x

the GValue to check

 

gst_value_set_int64_range ()

void
gst_value_set_int64_range (GValue *value,
                           gint64 start,
                           gint64 end);

Sets value to the range specified by start and end .

Parameters

value

a GValue initialized to GST_TYPE_INT64_RANGE

 

start

the start of the range

 

end

the end of the range

 

gst_value_get_int64_range_min ()

gint64
gst_value_get_int64_range_min (const GValue *value);

Gets the minimum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT64_RANGE

 

Returns

the minimum of the range


gst_value_get_int64_range_max ()

gint64
gst_value_get_int64_range_max (const GValue *value);

Gets the maximum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT64_RANGE

 

Returns

the maxumum of the range


gst_value_set_int64_range_step ()

void
gst_value_set_int64_range_step (GValue *value,
                                gint64 start,
                                gint64 end,
                                gint64 step);

Sets value to the range specified by start , end and step .

Parameters

value

a GValue initialized to GST_TYPE_INT64_RANGE

 

start

the start of the range

 

end

the end of the range

 

step

the step of the range

 

gst_value_get_int64_range_step ()

gint64
gst_value_get_int64_range_step (const GValue *value);

Gets the step of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_INT64_RANGE

 

Returns

the step of the range


GST_VALUE_HOLDS_DOUBLE_RANGE()

#define GST_VALUE_HOLDS_DOUBLE_RANGE(x) (G_VALUE_HOLDS((x), gst_double_range_get_type ()))

Checks if the given GValue contains a GST_TYPE_DOUBLE_RANGE value.

Parameters

x

the GValue to check

 

gst_value_set_double_range ()

void
gst_value_set_double_range (GValue *value,
                            gdouble start,
                            gdouble end);

Sets value to the range specified by start and end .

Parameters

value

a GValue initialized to GST_TYPE_DOUBLE_RANGE

 

start

the start of the range

 

end

the end of the range

 

gst_value_get_double_range_min ()

gdouble
gst_value_get_double_range_min (const GValue *value);

Gets the minimum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_DOUBLE_RANGE

 

Returns

the minimum of the range


gst_value_get_double_range_max ()

gdouble
gst_value_get_double_range_max (const GValue *value);

Gets the maximum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_DOUBLE_RANGE

 

Returns

the maxumum of the range


GST_VALUE_HOLDS_LIST()

#define GST_VALUE_HOLDS_LIST(x)         (G_VALUE_HOLDS((x), gst_value_list_get_type ()))

Checks if the given GValue contains a GST_TYPE_LIST value.

Parameters

x

the GValue to check

 

GST_VALUE_HOLDS_ARRAY()

#define GST_VALUE_HOLDS_ARRAY(x)        (G_VALUE_HOLDS((x), gst_value_array_get_type ()))

Checks if the given GValue contains a GST_TYPE_ARRAY value.

Parameters

x

the GValue to check

 

gst_value_list_append_value ()

void
gst_value_list_append_value (GValue *value,
                             const GValue *append_value);

Appends append_value to the GstValueList in value .

Parameters

value

a GValue of type GST_TYPE_LIST

 

append_value

the value to append.

[transfer none]

gst_value_list_prepend_value ()

void
gst_value_list_prepend_value (GValue *value,
                              const GValue *prepend_value);

Prepends prepend_value to the GstValueList in value .

Parameters

value

a GValue of type GST_TYPE_LIST

 

prepend_value

the value to prepend

 

gst_value_list_concat ()

void
gst_value_list_concat (GValue *dest,
                       const GValue *value1,
                       const GValue *value2);

Concatenates copies of value1 and value2 into a list. Values that are not of type GST_TYPE_LIST are treated as if they were lists of length 1. dest will be initialized to the type GST_TYPE_LIST.

Parameters

dest

an uninitialized GValue to take the result.

[out caller-allocates]

value1

a GValue

 

value2

a GValue

 

gst_value_list_merge ()

void
gst_value_list_merge (GValue *dest,
                      const GValue *value1,
                      const GValue *value2);

Merges copies of value1 and value2 . Values that are not of type GST_TYPE_LIST are treated as if they were lists of length 1.

The result will be put into dest and will either be a list that will not contain any duplicates, or a non-list type (if value1 and value2 were equal).

Parameters

dest

an uninitialized GValue to take the result.

[out caller-allocates]

value1

a GValue

 

value2

a GValue

 

gst_value_list_get_size ()

guint
gst_value_list_get_size (const GValue *value);

Gets the number of values contained in value .

Parameters

value

a GValue of type GST_TYPE_LIST

 

Returns

the number of values


gst_value_list_get_value ()

const GValue *
gst_value_list_get_value (const GValue *value,
                          guint index);

Gets the value that is a member of the list contained in value and has the index index .

Parameters

value

a GValue of type GST_TYPE_LIST

 

index

index of value to get from the list

 

Returns

the value at the given index.

[transfer none]


GST_VALUE_HOLDS_FRACTION()

#define GST_VALUE_HOLDS_FRACTION(x)     (G_VALUE_HOLDS((x), gst_fraction_get_type ()))

Checks if the given GValue contains a GST_TYPE_FRACTION value.

Parameters

x

the GValue to check

 

gst_value_set_fraction ()

void
gst_value_set_fraction (GValue *value,
                        gint numerator,
                        gint denominator);

Sets value to the fraction specified by numerator over denominator . The fraction gets reduced to the smallest numerator and denominator, and if necessary the sign is moved to the numerator.

Parameters

value

a GValue initialized to GST_TYPE_FRACTION

 

numerator

the numerator of the fraction

 

denominator

the denominator of the fraction

 

gst_value_get_fraction_numerator ()

gint
gst_value_get_fraction_numerator (const GValue *value);

Gets the numerator of the fraction specified by value .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION

 

Returns

the numerator of the fraction.


gst_value_get_fraction_denominator ()

gint
gst_value_get_fraction_denominator (const GValue *value);

Gets the denominator of the fraction specified by value .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION

 

Returns

the denominator of the fraction.


gst_value_fraction_multiply ()

gboolean
gst_value_fraction_multiply (GValue *product,
                             const GValue *factor1,
                             const GValue *factor2);

Multiplies the two GValue items containing a GST_TYPE_FRACTION and sets product to the product of the two fractions.

Parameters

product

a GValue initialized to GST_TYPE_FRACTION

 

factor1

a GValue initialized to GST_TYPE_FRACTION

 

factor2

a GValue initialized to GST_TYPE_FRACTION

 

Returns

FALSE in case of an error (like integer overflow), TRUE otherwise.


gst_value_fraction_subtract ()

gboolean
gst_value_fraction_subtract (GValue *dest,
                             const GValue *minuend,
                             const GValue *subtrahend);

Subtracts the subtrahend from the minuend and sets dest to the result.

Parameters

dest

a GValue initialized to GST_TYPE_FRACTION

 

minuend

a GValue initialized to GST_TYPE_FRACTION

 

subtrahend

a GValue initialized to GST_TYPE_FRACTION

 

Returns

FALSE in case of an error (like integer overflow), TRUE otherwise.


GST_VALUE_HOLDS_FRACTION_RANGE()

#define GST_VALUE_HOLDS_FRACTION_RANGE(x)    (G_VALUE_HOLDS((x), gst_fraction_range_get_type ()))

Checks if the given GValue contains a GST_TYPE_FRACTION_RANGE value.

Parameters

x

the GValue to check

 

gst_value_set_fraction_range ()

void
gst_value_set_fraction_range (GValue *value,
                              const GValue *start,
                              const GValue *end);

Sets value to the range specified by start and end .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION_RANGE

 

start

the start of the range (a GST_TYPE_FRACTION GValue)

 

end

the end of the range (a GST_TYPE_FRACTION GValue)

 

gst_value_get_fraction_range_min ()

const GValue *
gst_value_get_fraction_range_min (const GValue *value);

Gets the minimum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION_RANGE

 

Returns

the minimum of the range


gst_value_get_fraction_range_max ()

const GValue *
gst_value_get_fraction_range_max (const GValue *value);

Gets the maximum of the range specified by value .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION_RANGE

 

Returns

the maximum of the range


gst_value_set_fraction_range_full ()

void
gst_value_set_fraction_range_full (GValue *value,
                                   gint numerator_start,
                                   gint denominator_start,
                                   gint numerator_end,
                                   gint denominator_end);

Sets value to the range specified by numerator_start /denominator_start and numerator_end /denominator_end .

Parameters

value

a GValue initialized to GST_TYPE_FRACTION_RANGE

 

numerator_start

the numerator start of the range

 

denominator_start

the denominator start of the range

 

numerator_end

the numerator end of the range

 

denominator_end

the denominator end of the range

 

GST_VALUE_HOLDS_DATE_TIME()

#define GST_VALUE_HOLDS_DATE_TIME(x)    (G_VALUE_HOLDS((x), gst_date_time_get_type ()))

Checks if the given GValue contains a GST_TYPE_DATE_TIME value.

Parameters

x

the GValue to check

 

GST_VALUE_HOLDS_CAPS()

#define GST_VALUE_HOLDS_CAPS(x)         (G_VALUE_HOLDS((x), GST_TYPE_CAPS))

Checks if the given GValue contains a GST_TYPE_CAPS value.

Parameters

x

the GValue to check

 

gst_value_set_caps ()

void
gst_value_set_caps (GValue *value,
                    const GstCaps *caps);

Sets the contents of value to caps . A reference to the provided caps will be taken by the value .

Parameters

value

a GValue initialized to GST_TYPE_CAPS

 

caps

the caps to set the value to.

[transfer none]

gst_value_get_caps ()

const GstCaps *
gst_value_get_caps (const GValue *value);

Gets the contents of value . The reference count of the returned GstCaps will not be modified, therefore the caller must take one before getting rid of the value .

Parameters

value

a GValue initialized to GST_TYPE_CAPS

 

Returns

the contents of value .

[transfer none]


GST_VALUE_HOLDS_CAPS_FEATURES()

#define GST_VALUE_HOLDS_CAPS_FEATURES(x)        (G_VALUE_HOLDS((x), GST_TYPE_CAPS_FEATURES))

Checks if the given GValue contains a GST_TYPE_CAPS_FEATURES value.

Parameters

x

the GValue to check

 

gst_value_set_caps_features ()

void
gst_value_set_caps_features (GValue *value,
                             const GstCapsFeatures *features);

Sets the contents of value to features .

Parameters

value

a GValue initialized to GST_TYPE_CAPS_FEATURES

 

features

the features to set the value to

 

gst_value_get_caps_features ()

const GstCapsFeatures *
gst_value_get_caps_features (const GValue *value);

Gets the contents of value .

Parameters

value

a GValue initialized to GST_TYPE_CAPS_FEATURES

 

Returns

the contents of value .

[transfer none]


GST_VALUE_HOLDS_STRUCTURE()

#define GST_VALUE_HOLDS_STRUCTURE(x)            (G_VALUE_HOLDS((x), GST_TYPE_STRUCTURE))

Checks if the given GValue contains a GST_TYPE_STRUCTURE value.

Parameters

x

the GValue to check

 

gst_value_set_structure ()

void
gst_value_set_structure (GValue *value,
                         const GstStructure *structure);

Sets the contents of value to structure . The actual

Parameters

value

a GValue initialized to GST_TYPE_STRUCTURE

 

structure

the structure to set the value to

 

gst_value_get_structure ()

const GstStructure *
gst_value_get_structure (const GValue *value);

Gets the contents of value .

Parameters

value

a GValue initialized to GST_TYPE_STRUCTURE

 

Returns

the contents of value .

[transfer none]


GST_VALUE_HOLDS_BUFFER()

#define GST_VALUE_HOLDS_BUFFER(x)       (G_VALUE_HOLDS((x), GST_TYPE_BUFFER))

Checks if the given GValue contains a GST_TYPE_BUFFER value.

Parameters

x

the GValue to check

 

gst_value_get_buffer()

#define         gst_value_get_buffer(v)         GST_BUFFER_CAST (g_value_get_boxed(v))

Receives a GstBuffer as the value of v . Does not return a reference to the buffer, so the pointer is only valid for as long as the caller owns a reference to v .

Parameters

v

a GValue to query

 

Returns

buffer.

[transfer none]


gst_value_set_buffer()

#define         gst_value_set_buffer(v,b)       g_value_set_boxed((v),(b))

Sets b as the value of v . Caller retains reference to buffer.

Parameters

v

a GValue to receive the data

 

b

a GstBuffer to assign to the GstValue.

[transfer none]

gst_value_take_buffer()

#define         gst_value_take_buffer(v,b)      g_value_take_boxed(v,(b))

Sets b as the value of v . Caller gives away reference to buffer.

Parameters

v

a GValue to receive the data

 

b

a GstBuffer to assign to the GstValue.

[transfer full]

GST_VALUE_HOLDS_SAMPLE()

#define GST_VALUE_HOLDS_SAMPLE(x)       (G_VALUE_HOLDS((x), GST_TYPE_SAMPLE))

Checks if the given GValue contains a GST_TYPE_SAMPLE value.

Parameters

x

the GValue to check

 

gst_value_get_sample()

#define         gst_value_get_sample(v)         GST_SAMPLE_CAST (g_value_get_boxed(v))

Receives a GstSample as the value of v . Does not return a reference to the sample, so the pointer is only valid for as long as the caller owns a reference to v .

Parameters

v

a GValue to query

 

Returns

sample.

[transfer none]


gst_value_set_sample()

#define         gst_value_set_sample(v,b)       g_value_set_boxed((v),(b))

Sets b as the value of v . Caller retains reference to sample.

Parameters

v

a GValue to receive the data

 

b

a GstSample to assign to the GstValue.

[transfer none]

gst_value_take_sample()

#define         gst_value_take_sample(v,b)      g_value_take_boxed(v,(b))

Sets b as the value of v . Caller gives away reference to sample.

Parameters

v

a GValue to receive the data

 

b

a GstSample to assign to the GstValue.

[transfer full]

GST_VALUE_LESS_THAN

#define GST_VALUE_LESS_THAN              (-1)

Indicates that the first value provided to a comparison function (gst_value_compare()) is lesser than the second one.


GstValueCompareFunc ()

gint
(*GstValueCompareFunc) (const GValue *value1,
                        const GValue *value2);

Used together with gst_value_compare() to compare GValue items.

Parameters

value1

first value for comparison

 

value2

second value for comparison

 

Returns

one of GST_VALUE_LESS_THAN, GST_VALUE_EQUAL, GST_VALUE_GREATER_THAN or GST_VALUE_UNORDERED


GstValueSerializeFunc ()

gchar *
(*GstValueSerializeFunc) (const GValue *value1);

Used by gst_value_serialize() to obtain a non-binary form of the GValue.

Free-function: g_free

Parameters

value1

a GValue

 

Returns

the string representation of the value.

[transfer full]


GstValueDeserializeFunc ()

gboolean
(*GstValueDeserializeFunc) (GValue *dest,
                            const gchar *s);

Used by gst_value_deserialize() to parse a non-binary form into the GValue.

Parameters

dest

a GValue

 

s

a string

 

Returns

TRUE for success


gst_value_is_fixed ()

gboolean
gst_value_is_fixed (const GValue *value);

Tests if the given GValue, if available in a GstStructure (or any other container) contains a "fixed" (which means: one value) or an "unfixed" (which means: multiple possible values, such as data lists or data ranges) value.

Parameters

value

the GValue to check

 

Returns

true if the value is "fixed".


gst_value_register ()

void
gst_value_register (const GstValueTable *table);

Registers functions to perform calculations on GValue items of a given type. Each type can only be added once.

Parameters

table

structure containing functions to register

 

gst_value_init_and_copy ()

void
gst_value_init_and_copy (GValue *dest,
                         const GValue *src);

Initialises the target value to be of the same type as source and then copies the contents from source to target.

Parameters

dest

the target value.

[out caller-allocates]

src

the source value

 

gst_value_serialize ()

gchar *
gst_value_serialize (const GValue *value);

tries to transform the given value into a string representation that allows getting back this string later on using gst_value_deserialize().

Free-function: g_free

Parameters

value

a GValue to serialize

 

Returns

the serialization for value or NULL if none exists.

[transfer full]


gst_value_deserialize ()

gboolean
gst_value_deserialize (GValue *dest,
                       const gchar *src);

Tries to deserialize a string into the type specified by the given GValue. If the operation succeeds, TRUE is returned, FALSE otherwise.

Parameters

dest

GValue to fill with contents of deserialization.

[out caller-allocates]

src

string to deserialize

 

Returns

TRUE on success


gst_value_compare ()

gint
gst_value_compare (const GValue *value1,
                   const GValue *value2);

Compares value1 and value2 . If value1 and value2 cannot be compared, the function returns GST_VALUE_UNORDERED. Otherwise, if value1 is greater than value2 , GST_VALUE_GREATER_THAN is returned. If value1 is less than value2 , GST_VALUE_LESS_THAN is returned. If the values are equal, GST_VALUE_EQUAL is returned.

Parameters

value1

a value to compare

 

value2

another value to compare

 

Returns

comparison result


gst_value_can_compare ()

gboolean
gst_value_can_compare (const GValue *value1,
                       const GValue *value2);

Determines if value1 and value2 can be compared.

Parameters

value1

a value to compare

 

value2

another value to compare

 

Returns

TRUE if the values can be compared


gst_value_union ()

gboolean
gst_value_union (GValue *dest,
                 const GValue *value1,
                 const GValue *value2);

Creates a GValue corresponding to the union of value1 and value2 .

Parameters

dest

the destination value.

[out caller-allocates]

value1

a value to union

 

value2

another value to union

 

Returns

TRUE if the union suceeded.


gst_value_can_union ()

gboolean
gst_value_can_union (const GValue *value1,
                     const GValue *value2);

Determines if value1 and value2 can be non-trivially unioned. Any two values can be trivially unioned by adding both of them to a GstValueList. However, certain types have the possibility to be unioned in a simpler way. For example, an integer range and an integer can be unioned if the integer is a subset of the integer range. If there is the possibility that two values can be unioned, this function returns TRUE.

Parameters

value1

a value to union

 

value2

another value to union

 

Returns

TRUE if there is a function allowing the two values to be unioned.


gst_value_subtract ()

gboolean
gst_value_subtract (GValue *dest,
                    const GValue *minuend,
                    const GValue *subtrahend);

Subtracts subtrahend from minuend and stores the result in dest . Note that this means subtraction as in sets, not as in mathematics.

Parameters

dest

the destination value for the result if the subtraction is not empty. May be NULL, in which case the resulting set will not be computed, which can give a fair speedup.

[out caller-allocates]

minuend

the value to subtract from

 

subtrahend

the value to subtract

 

Returns

TRUE if the subtraction is not empty


gst_value_can_subtract ()

gboolean
gst_value_can_subtract (const GValue *minuend,
                        const GValue *subtrahend);

Checks if it's possible to subtract subtrahend from minuend .

Parameters

minuend

the value to subtract from

 

subtrahend

the value to subtract

 

Returns

TRUE if a subtraction is possible


gst_value_intersect ()

gboolean
gst_value_intersect (GValue *dest,
                     const GValue *value1,
                     const GValue *value2);

Calculates the intersection of two values. If the values have a non-empty intersection, the value representing the intersection is placed in dest , unless NULL. If the intersection is non-empty, dest is not modified.

Parameters

dest

a uninitialized GValue that will hold the calculated intersection value. May be NULL if the resulting set if not needed.

[out caller-allocates][transfer full]

value1

a value to intersect

 

value2

another value to intersect

 

Returns

TRUE if the intersection is non-empty


gst_value_can_intersect ()

gboolean
gst_value_can_intersect (const GValue *value1,
                         const GValue *value2);

Determines if intersecting two values will produce a valid result. Two values will produce a valid intersection if they have the same type, or if there is a method (registered by gst_value_register_intersect_func()) to calculate the intersection.

Parameters

value1

a value to intersect

 

value2

another value to intersect

 

Returns

TRUE if the values can intersect


gst_value_is_subset ()

gboolean
gst_value_is_subset (const GValue *value1,
                     const GValue *value2);

Check that value1 is a subset of value2 .

Return: TRUE is value1 is a subset of value2

Parameters

value1

a GValue

 

value2

a GValue

 

gst_value_array_append_value ()

void
gst_value_array_append_value (GValue *value,
                              const GValue *append_value);

Appends append_value to the GstValueArray in value .

Parameters

value

a GValue of type GST_TYPE_ARRAY

 

append_value

the value to append

 

gst_value_array_get_size ()

guint
gst_value_array_get_size (const GValue *value);

Gets the number of values contained in value .

Parameters

value

a GValue of type GST_TYPE_ARRAY

 

Returns

the number of values


gst_value_array_get_value ()

const GValue *
gst_value_array_get_value (const GValue *value,
                           guint index);

Gets the value that is a member of the array contained in value and has the index index .

Parameters

value

a GValue of type GST_TYPE_ARRAY

 

index

index of value to get from the array

 

Returns

the value at the given index.

[transfer none]


gst_value_array_prepend_value ()

void
gst_value_array_prepend_value (GValue *value,
                               const GValue *prepend_value);

Prepends prepend_value to the GstValueArray in value .

Parameters

value

a GValue of type GST_TYPE_ARRAY

 

prepend_value

the value to prepend

 

gst_value_fixate ()

gboolean
gst_value_fixate (GValue *dest,
                  const GValue *src);

Fixate src into a new value dest . For ranges, the first element is taken. For lists and arrays, the first item is fixated and returned. If src is already fixed, this function returns FALSE.

Parameters

dest

the GValue destination

 

src

the GValue to fixate

 

Returns

true if dest contains a fixated version of src .

Types and Values

GST_FOURCC_FORMAT

#define GST_FOURCC_FORMAT "c%c%c%c"

Can be used together with GST_FOURCC_ARGS to properly output a guint32 fourcc value in a printf()-style text message.

1
printf ("fourcc: %" GST_FOURCC_FORMAT "\n", GST_FOURCC_ARGS (fcc));

GST_TYPE_INT_RANGE

#define GST_TYPE_INT_RANGE               gst_int_range_get_type ()

a GValue type that represents an integer range

Returns

the GType of GstIntRange


GST_TYPE_BITMASK

#define GST_TYPE_BITMASK                 gst_bitmask_get_type ()

a GValue type that represents a 64-bit bitmask.

Returns

the GType of GstBitmask (which is not explicitly typed)


GST_TYPE_INT64_RANGE

#define GST_TYPE_INT64_RANGE             gst_int64_range_get_type ()

a GValue type that represents an gint64 range

Returns

the GType of GstInt64Range


GST_TYPE_DOUBLE_RANGE

#define GST_TYPE_DOUBLE_RANGE            gst_double_range_get_type ()

a GValue type that represents a floating point range with double precission

Returns

the GType of GstIntRange


GST_TYPE_LIST

#define GST_TYPE_LIST                    gst_value_list_get_type ()

a GValue type that represents an unordered list of GValue values. This is used for example to express a list of possible values for a field in a caps structure, like a list of possible sample rates, of which only one will be chosen in the end. This means that all values in the list are meaningful on their own.

Returns

the GType of GstValueList (which is not explicitly typed)


GST_TYPE_ARRAY

#define GST_TYPE_ARRAY                   gst_value_array_get_type ()

a GValue type that represents an ordered list of GValue values. This is used to express a set of values that is meaningful only in their specific combination and order of values. Each value on its own is not particularly meaningful, only the ordered array in its entirety is meaningful. This is used for example to express channel layouts for multichannel audio where each channel needs to be mapped to a position in the room.

Returns

the GType of GstArrayList (which is not explicitly typed)


GST_TYPE_FRACTION

#define GST_TYPE_FRACTION                gst_fraction_get_type ()

a GValue type that represents a fraction of an integer numerator over an integer denominator

Returns

the GType of GstFraction (which is not explicitly typed)


GST_TYPE_FRACTION_RANGE

#define GST_TYPE_FRACTION_RANGE            gst_fraction_range_get_type ()

a GValue type that represents a GstFraction range

Returns

the GType of GstFractionRange


GST_VALUE_EQUAL

#define GST_VALUE_EQUAL                   0

Indicates that the first value provided to a comparison function (gst_value_compare()) is equal to the second one.


GST_VALUE_GREATER_THAN

#define GST_VALUE_GREATER_THAN            1

Indicates that the first value provided to a comparison function (gst_value_compare()) is greater than the second one.


GST_VALUE_UNORDERED

#define GST_VALUE_UNORDERED               2

Indicates that the comparison function (gst_value_compare()) can not determine a order for the two provided values.


struct GstValueTable

struct GstValueTable {
  GType type;
  GstValueCompareFunc compare;
  GstValueSerializeFunc serialize;
  GstValueDeserializeFunc deserialize;
};

VTable for the GValue type .